[chuck-users] odd hid issue (touchpad)

Kassen signal.automatique at gmail.com
Sat Jul 18 10:14:14 EDT 2009


I checked in a program the HID variables for the mouse and trackpad are the
> same X-Axis Y-Axis. But 'chuck' probably just calls some interface that is
> available on the OS. That is how it works on Mac OS X. So if the OS admits
> PS/2 devices, then should feed some information into that interface, which
> is what 'chuck' then reports.

Yes, that's basically what I imagined was going on as well.

> Though some older protocols like SCSI have advantages over more modern,
> consumer friendly ones like USB, I  don't there are any system bus issues
> for these, as one has some intermediate hardware that provides the
> communication. In the 1970s I assembled a computer, that wrote the keyboard
> characters directly into memory, which the CPU checked in a loop. This is
> highly inefficient way to handle it.

Ah, yes, I would indeed imagine that would be fast. For all I know that's
what Apple is doing now... Having full control over the hardware specs would
allow you to do that. The only downside that I can see would be that
spilling drinks in the keyboard might cause the memory itself to be fried
but I suppose you might be able to have some sort of protection against

>  This might also be limited by factors like maximum poll-rate and
>> resolution;
> For the USB keyboards I have checked, this seems to be limitation of the
> keyboard, that is, even before the data is sent to the computer. This is
> because it differs with the keyboard. The computer is so fast that it easily
> can handle any human typed key roll-over. The slow USB 1 bus is on about 12
> Mb/s, which should admit for tens of thousands of key stroke in a tenth of a
> second.

I meant PS/2 might be limited there. In recent years the quality of high
performance mice has gone up quite a bit, probably originally inspired by
games like Quake. It was chiefly mouse signals that I was refering to. Sadly
(I feel) the quality of keyboards hasn't made the same progression and
keyboard ghosting is now typically worse then it was on keyboards from the

> When experimenting with the diatonic key map, the problem is mostly due to
> other process running. One notorious one is looking for RSS feeds.

Yes, I was a bit disappointed  when I found out about that as well though I
do think that's a quite different issue.

I think I tried a Mac keyboard once on a Windows, finding it not working.
> One needs to have a driver installed. Each device may require its own. The
> USB HID interface unifies those, so that only one driver is needed, which
> then can be supplied by the OS. The latest version of this USB HID interface
> or standard was issued this year. So perhaps it was not available when
> 'chuck' was written.
Odd. I've never seen a keyboard not work, I think. Special keys (like volume
or "sleep" ones) may need a driver in my experience but the keyboard itself
always worked. I think you can even take a ps/2 keyboard, use a USB adapter
and plug it straight into a Mac, provided you are willing to remap some
stuff to the "Apple" and related keys.

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